''Geosternbergia'' is an extinct
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
of
pteranodontid pterodactyloid pterosaur
Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the Order (biology), order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cre ...
from the
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...
geological period of
North America. ''Geosternbergia'' was one of the largest pterosaur genera, and had a wingspan of up to .
Discovery and history
The first fossils of ''Geosternbergia'' were collected by American paleontologist
George F. Sternberg
George Fryer Sternberg (1883–1969) was a paleontologist best known for his discovery in Gove County, Kansas of the "fish-within-a-fish" of ''Xiphactinus audax'' with a recently eaten ''Gillicus arcuatus'' within its stomach. Sternberg was bor ...
in 1952 from the lower portion of the
Niobrara Formation
The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is compose ...
. The fossils of the animal looked similar to those of the species ''
Pteranodon longiceps'', but the crests were set upright and in a slightly different position. In 1958, Sternberg and paleontologist
Myrl V. Walker published a study about this peculiar find.
In 1966, American paleontologist
John Christian Harksen
John is a common English name and surname:
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* John (surname)
John may also refer to:
New Testament
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* Gospel of John, a title often shortened to John
* First Epistle of John, often shortened to 1 John
* Second E ...
assigned the specimens found as a new species of ''Pteranodon'' called ''P. sternbergi'' due to its distinct upright crest that set it apart from ''P. longiceps''.
Halsey W. Miller
Halsey may refer to:
People
*Halsey (surname), including a list of people
* Halsey (singer) (born 1994), American singer and songwriter
*Halsey baronets, a title in the Baronetage of the United Kingdom
*Halsey Beshears, a Republican politician fr ...
however, concluded a revision of the different species of ''Pteranodon'' in 1971, and created three different
subgenera
In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed betwee ...
. One of which was ''Sternbergia'', which consisted of the ''Pteranodon'' specimens with upright crests. ''P. sternbergi'' was assigned to this subgenus along with another species called ''P. walkeri'', but Miller then found out that the name ''Sternbergia'' had been preoccupied, so he changed it into ''Geosternbergia'' instead.
Paleontologists like
S. Christopher Bennett
S is the nineteenth letter of the English alphabet.
S may also refer to:
History
* an Anglo-Saxon charter's number in Peter Sawyer's, catalogue Language and linguistics
* Long s (ſ), a form of the lower-case letter s formerly used where "s ...
consider ''Geosternbergia'' to be older than ''P. longiceps'', and therefore the direct ancestor of that species.
[
]
The most complete example of the species, currently in the collections of the University of Alberta Laboratory for Vertebrate Paleontology as specimen number UALVP 24238, is a partially-articulated sub-adult fossil with a wingspan of about . The skeleton is missing only parts of the skull and the ends of the wings and feet, was discovered in 1974 near Utica, Kansas
Utica is a city in Ness County, Kansas, United States. As of the 2020 census, the population of the city was 99.
History
The first post office in Utica was established in 1879.
Utica was named by early pioneer C.W. Bell who was from Utica, N ...
. The fossil was found by Richard C. Fox and Allen Lindoe in rocks belonging to the lower part of the Smoky Hill Chalk Member
The Smoky Hill Chalk Member of the Niobrara Chalk formation is a Cretaceous conservation Lagerstätte, or fossil rich geological formation, known primarily for its exceptionally well-preserved marine reptiles. Named for the Smoky Hill River, the S ...
of the Niobrara Formation
The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is compose ...
. These rocks date to the late Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded b ...
or early Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. ...
stage, about 86 million years ago. In 2010
File:2010 Events Collage New.png, From top left, clockwise: The 2010 Chile earthquake was one of the strongest recorded in history; The Eruption of Eyjafjallajökull in Iceland disrupts air travel in Europe; A scene from the opening ceremony of ...
, a paper by Alexander W.A. Kellner argued that this specimen was different enough from ''G. sternbegi'' that it should be re-classified as its own genus and species, which he named ''Dawndraco kanzai''. This generic name combined the Dawn deity of the Iroquois
The Iroquois ( or ), officially the Haudenosaunee ( meaning "people of the longhouse"), are an Iroquoian-speaking confederacy of First Nations peoples in northeast North America/ Turtle Island. They were known during the colonial years to ...
with a Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
''draco'', " dragon". The specific name Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany), the two-part (bino ...
refers to the Kanza tribe of Kansas
Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to ...
.[ Kellner thought that several features of the skeleton supported his hypothesis that ''D. kanzai'' was a unique species, most notably its unique snout, which does not strongly taper towards the tip as in female ''Pteranodon'' specimens, with the upper and lower margins running almost parallel instead. Kellner thought this meant the specimen must have had a crest running along the length of the snout. However, a re-examination of the fossil published in 2017 by Elizabeth Martin-Silverstone and colleagues argued that the differences in the snout were more likely due to male pteranodontids having longer, broader bills than the more complete female specimens Kellner used for comparison. Martin-Silverstone concluded that "''Dawndraco''" was simply a male ''G. sternbergi'' with a very long bill with a gradual taper.]
''Geosternbergia'' fossils are known from the Niobrara Niobrara may refer to:
* Niobrara, Nebraska
* Niobrara County, Wyoming
* Niobrara River
* Niobrara National Scenic River
* Niobrara Formation, a geological unit
* Niobrara Township, Knox County, Nebraska
Niobrara Township is one of thirty towns ...
and Sharon Springs Formations of the central United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...
. ''Geosternbergia'' existed as a group for more than four million years during the late Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded b ...
– early Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...
stages of the Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
period. The genus is present in the lower the Niobrarra Formation except for the upper two; in 2003, Kenneth Carpenter surveyed the distribution and dating of fossils in this formation, demonstrating that ''Geosternbergia sternbergi'' existed there from 88–85 million years ago, while the species later named ''G. maiseyi'' existed between 81.5 and 80.5 million years ago.
Description
Size
''Geosternbergia'' was among the largest pterosaurs, with the wingspan of most adults ranging between . No complete skulls of adult males have been found, but a nearly complete lower jaw has been estimated at long.[Zimmerman, H., Preiss, B., and Sovak, J. (2001). ''Beyond the Dinosaurs!: sky dragons, sea monsters, mega-mammals, and other prehistoric beasts'', Simon and Schuster. .] While most specimens are found crushed, enough fossils exist to put together a detailed description of the animal. ''Geosternbergia sternbergi'' was very similar to the more well-known pterosaur species ''Pteranodon longiceps'' and is often considered simply an earlier species of ''Pteranodon'' itself. It is different from ''Pteranodon'' mainly due to its earlier time period and broader, more upright crest.[
]
Skull and beak
The upright cranial crest A crest is any of various anatomical features appearing as a raised point or ridge, most prominently those on the head or back of an animal.
*A part of a bone:
**Sagittal crest
** Cnemial crest
** Iliac crest
**Frontal crest
**Infratemporal crest
* ...
of ''Geosternbergia'' is its distinctive characteristic. These crests consisted of skull bones (frontals) projecting upward and backward from the skull. The size and shape of these crests varied due to a number of factors, including age, sex, and species. Male ''G. sternbergi'', the older species of the two described to date, had a larger vertical crest with a broad forward projection, while ''G. maiseyi'' had a short, rounded vertical crest and was generally smaller. Females of both species were smaller and bore small, rounded crests.[ The crests were probably mainly display structures, though they may have had other functions as well.][
Unlike the earlier pterosaurs, such as the rhamphorhynchids and the ]pterodactylid
Pterodactylidae is a controversial group of pterosaurs. During the 2000s and 2010s, several competing definitions for the various Jurassic pterodactyloid groups were proposed. Pereda-Suberbiola ''et al.'' (2012) used Fabien Knoll's (2000) defini ...
s, ''Geosternberigia'' had a toothless beak
The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for fo ...
that was made of solid, bony margins that projected from the base of the jaws, similar to modern-day birds
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
. The structure of the beaks were long, slender, and ended in thin, sharp points. Its maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The ...
was also found to be longer than the mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bon ...
, and was curved upward.
Classification
''Geosternbergia'' was traditionally considered a species, or occasionally subgenus, of the similar pterosaur ''Pteranodon
''Pteranodon'' (); from Ancient Greek (''pteron'', "wing") and (''anodon'', "toothless") is a genus of pterosaur that included some of the largest known flying reptiles, with ''P. longiceps'' having a wingspan of . They lived during the late C ...
'', in most major studies of pteranodontians through the 1990s. However, a 2010 review of the group by A.W.A. Kellner suggested that ''Pteranodon sternbergi'' was different enough from ''P. longiceps'' to belong in a distinct genus, to which Kellner also referred a new species, ''Geosternbergia maiseyi''.[ Earlier, pterosaur researcher Chris Bennett had considered the ''G. maiseyi'' specimen an adult male ''P. longiceps''.
Below is a ]cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...
showing the phylogenetic placement of this genus within Pteranodontia from Andres and Myers (2013).
Paleobiology
Sexual variation
Adult ''Geosternbergia'' specimens may be divided into two distinct size classes, small and large, with the large size class being about one and a half times larger than the small, and the small being twice as common as the large. Both size classes lived alongside each other, and while researchers had previously suggested that they represent different species, Christopher Bennett showed that the differences between them are consistent with the concept that they represent females and males, and that ''Geosternbergia'' species were sexually dimorphic
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
. Skulls from the larger size class preserve large, upward and backward pointing crests, while the crests of the smaller size class are small and triangular. Some larger skulls also show evidence of a second crest that extended long and low, toward the tip of the beak, which is not seen in smaller specimens.
The gender of the different size classes was determined, not from the skulls, but from the pelvic bones. Contrary to what may be expected, the smaller size class had disproportionately large and wide-set pelvic bones. Bennett interpreted this as indicating a more spacious birth canal, through which eggs would pass. He concluded that the small size class with small, triangular crests represent females, and the larger, large-crested specimens represent males.[
Note that the overall size and crest size also corresponds to age. Immature specimens are known from both females and males, and immature males often have small crests similar to adult females. Therefore, it seems that the large crests only developed in males when they reached their large, adult size, making the gender of immature specimens difficult to establish from partial remains.]
The fact that females appear to have outnumbered males two to one suggests that, as with modern animals with size-related sexual dimorphism, such as sea lion
Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. ...
s and other pinniped
Pinnipeds (pronounced ), commonly known as seals, are a widely range (biology), distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammal, marine mammals. They comprise the extant taxon, extant family (biology ...
s, ''Geosternbergia'' might have been polygynous
Polygyny (; from Neoclassical Greek πολυγυνία (); ) is the most common and accepted form of polygamy around the world, entailing the marriage of a man with several women.
Incidence
Polygyny is more widespread in Africa than in any o ...
, with a few males competing for association with groups consisting of large numbers of females. Similar to modern pinnipeds, ''Geosternbergia'' may have competed to establish territory on rocky, offshore rookeries, with the largest, and largest-crested, males gaining the most territory and having more success mating with females. The crests of male ''Geosternbergia'' would not have been used in competition, but rather as "visual dominance-rank symbols", with display rituals taking the place of physical competition with other males. If this hypothesis
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can testable, test it. Scientists generally base scientific hypotheses on prev ...
is correct, it also is likely that male ''Geosternbergia'' played little to no part in rearing the young; such a behavior is not found in the males of modern polygynous animals who father many offspring at the same time.[
]
See also
* List of pterosaur genera
* Timeline of pterosaur research
* Pterosaur size
References
{{Portal bar, Paleontology, Cretaceous, United States
Late Cretaceous pterosaurs of North America
Pteranodontians
Taxa named by Alexander Kellner
Fossil taxa described in 1978